A similar thing happened to me with one of my Chase cards 2 years ago. I earned the SUB in the first billing cycle due to thousands of dollars of gross charges, most of which were refunded in the same cycle. I booked an expensive flight, had to cancel and rebook when needs changed, and then had to re-cancel and book a third time when needs changed again. I wasn't gaming the system; the changes were all legit and unforeseeable. Because it was not my intent to game the system I made sure to continue using the card to meet the SUB spending target with net charges during the offer period. I suggest you do the same. Then, if Chase ever does take adverse action against you (unlikely, but possible) you'll have a defense of acting in good faith.